AggregatedEntityClass

AggregatedEntityClass[class,"prop"->f] represents an entity class containing a single entity with the property prop whose value is the result of applying the function f to the whole specified entity class.

AggregatedEntityClass[class,{prop1->f1,prop2->f2,…}] constructs multiple properties propi obtained by applying fi to class.

AggregatedEntityClass[class,propspec,gprop] forms groups of elements of class according to their values of the property gprop, then generates an entity class with an entity for each of these groups. 

AggregatedEntityClass[class,propspec,"pname"->f] forms groups according to the values obtained by applying the entity function f, with the resulting property named pname.

AggregatedEntityClass[class,propspec,{gspec1,gspec2,…}] forms groups for which the set of values defined by the gspeci is distinct. 

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